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1.
金窝子金矿田位于中朝—塔里木板块与哈萨克斯坦板块俯冲碰撞带南缘的甘—新北山中带，是受断裂构造控制的岩浆热液型金矿床。区域构造格局控制成矿带的分布，不同构造单元具有不同的控矿构造型式。金矿田内基本构造格局是走向：NE、倾向NW的低角度逆冲断层及其伴生(派)生的同走向高角度逆冲断层、紧闭褶皱以及与其垂直的高角度横张断层组成的推覆构造体系。NE向低角度逆冲断层控制蚀变糜棱岩型金矿化(以210金矿床为代表)，NNW向高角度横张断层控制石英脉型金矿化(以金窝子金矿床为代表)，而NE向高角度逆冲断层和紧闭褶皱中无金矿化。NE向低角度断层不仅是重要的含矿构造，而且在成矿过程中起着控制成矿物理化学界面的作用。所以，金窝子金矿田2种不同金矿化类型是同一成矿作用在不同控矿构造动力学条件下的具体表现。 相似文献
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金窝子金矿田位于新甘交界的哈密地区,是北山地区最为重要的金矿田之一,其大地构造背景处于哈萨克斯坦—准噶尔板块与塔里木板块交汇部位东北缘的北山裂谷;断裂构造是矿田内最为重要的控矿因素.文章对矿田内主要的控矿断裂构造特征和断裂构造控矿规律特征进行了研究,F210韧脆性剪切断裂带为矿田内的主干断裂,该断裂的逆冲破碎带为210金矿床的直接控矿构造,控制了蚀变岩型金矿化的发育,由逆冲剪切产生的叠瓦式逆断层不含矿,而近SN向缓倾斜构造控制了210金矿床石英脉型矿化的发育:由F210韧脆性剪切断裂逆冲作用在金窝子岩体内形成的近SN向高角度追踪张性断裂控制了金窝子金矿床石英脉型矿体的形态、产状及成矿元素的分布;在对构造控矿作用研究的基础上,建立了矿区的控矿构造格架. 相似文献
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粤西推覆构造系统对金银及多金属矿床的控制 总被引：4，自引：1，他引：3
粤西推覆构造系统主要形成于海西-印支期,构造型式属褶皱式逆冲推覆构造,扩展方式为前展式,外来系统为前震旦系、震旦系和塞武系,原地系统为泥盆系、石炭系,次级逆冲断裂带多为上陡下缓的犁状形态。在横剖面上推覆构造系统中的构造带组合较齐全,且不同的构造带、构造部位成矿和控矿的作用不同,可分为:①断坪滑覆带中的矿床——新榕锰矿及银铅矿化;②推覆隆起韧性剪切带中的矿床——河台金矿;③断坡突起韧性剪切带中的矿床——大沟谷金矿;④推覆褶皱-冲断带中的矿床——大降坪硫铁矿;⑤盆内褶断带中的矿床——石径金矿;⑥前缘剥离拉伸带中的矿床——长坑金银矿;这些不同类型的矿床所具有的相关性和一致性,表明除地层岩性外推覆构造系统对该区金银及多金属矿的成矿和控矿作用。 相似文献
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阐明逆冲推覆构造地理分布,较全面论述逆冲推覆构造地质特征,系统概括逆冲推覆构造对铀成矿作用。逆冲推覆构造不但形成了导、运、移、储完备的三维立体构造网络系统,而且使贯通基底的构造复活,诱发次火山岩浆侵入,形成了岩性差异明显并具多层岩性结构的“立交”式岩层构造组合,创造了有利于成矿的一个封闭、半封闭的地质环境。推覆体下隐伏构造是岩浆侵入、矿液运移的良好通道和存储空间,致使深部成矿热液在局部富集形成矿体。矿化部值一个足富集于次火山岩接触带产状变化或形态变异处;另一个是富集于隐伏逆掩断层与基底NE向构造交汇的复合部位。 相似文献
5.
本文通过研究早阳金矿重点工作区构造变形现象,分析其构造变形几何学、运动学特征,区分构造活动期次,探讨与金成矿相关的构造期次。早阳金矿大地构造位置位于秦岭商丹缝合带与勉略缝合带之间,属南秦岭构造带,银杏坝-神河韧性滑脱逆冲推覆带。该金矿位于安康北部金成矿带内,为新发现的金矿床,且其控矿构造、赋矿层位、矿体围岩岩性等特征均与带内其它金矿不同。早阳金矿区构造变形复杂,经历多期构造事件叠加,发育区域性北西西向逆掩推覆、构造置换、韧性剪切带、掩卧褶皱等,与金成矿相关的构造活动为北西西向韧性剪切活动,近南北向挤压造成的北西西向脆性断裂为含金热液提供上侵通道。 相似文献
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普兰店元台逆冲覆构造为典型双重塑冲构造,以上叠式扩展而成。在自南向北逆冲过程中,形成褶皱推覆体,滞后断层,撕裂断层,反冲断层,并进一步形成构造窗和飞来峰。推覆构造形成于Ｊ２－Ｊ３,逆冲推覆后期,花岗闪长斑岩逆冲推覆构造就位,其所携带的成矿热液中有利部位富成金矿。 相似文献
7.
休宁桃溪断裂破碎带构造解析及其区域控矿作用启示 总被引：1，自引：0，他引：1
位于休宁县-歙县整装勘查区北西缘的休宁桃溪构造破碎带,岩石破碎,矿化蚀变强烈。详细的构造研究从中解析出逆冲推覆、左行平移作用、正断层作用和右行平移作用等多起变形。带中花岗斑岩侵入及金多金属矿矿化与构造的关系研究表明,逆冲推覆构造为成矿前构造,北东向平移断层控制了区内岩浆岩的分布,以北东向为主的正断层是成矿期构造,而右行平移断层是成矿后构造。本构造破碎带的多期变形及其与成矿关系可以为休宁县-歙县整装勘查区的构造控矿作用提供勘查。 相似文献
8.
漠滨脆—韧性剪切带型金矿床控矿构造研究 总被引：4，自引：0，他引：4
层间右旋逆冲脆—韧性剪切带构造控制漠滨金矿床。剪切带变形过程经历了早、中、晚3个阶段。而金矿化的形成和富集又与剪切带多阶段的演化密切相关,金矿化是剪切构造作用形成的。因此,剪切带既是控矿因素,又是重要的成矿机制,属层间逆冲脆—韧性剪切带型金矿床。 相似文献
9.
乐马厂银矿逆冲推覆构造特征及控矿作用 总被引：4，自引：0，他引：4
乐马厂大型独立银矿床的总体构造格架为逆冲推覆的构造体系，文章在分析区域地质构造背景和矿区地质构造特征的基础上，着重研究了该矿床叠瓦式逆冲推覆构造的地质构造特征及其控矿作用，论述了矿区逆冲推覆构造为燕山晚期形成的褶皱式逆冲推覆构造类型，其推覆运动形式为自NE向SW的右旋剪切运动，扩展方式为后展式，逆冲推覆构造为本区银矿床的形成创造了一个独特的极为有利的成矿构造环境，并控制了银矿体的形成，定位和空间分布规律，强调了以逆冲推覆断裂系统控矿为主，推覆体系统和掩复体系统次之的控矿规律。 相似文献
10.
开滦唐山矿逆冲推覆构造及其控煤作用 总被引：4，自引：0，他引：4
中生代形成的逆冲推覆构造对煤层影响很大。以位于唐山块陷之上开平煤田西北侧的开滦唐山矿区域背景分析为基础,从研究构造规律出发,通过几何学、运动学和动力学分析,主要探讨了以FIII逆断层为主体的逆冲推覆构造特征。结果显示,唐山矿推覆构造的走向与煤田内褶皱轴大致平行,沿地层走向呈NE向;其以前展式扩展方式自NW向SE方向逆冲;燕山运动早-中期,库拉-太平洋板块与欧亚板块的相互强烈挤压作用是该推覆构造的主要动力来源。另外,受褶皱和断层等构造控制,特别是受推覆构造的控制,唐山矿煤层厚度变化显著,局部出现煤仓。 相似文献
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<正>Fourteen graptolite species of the Late Tremadoc and Early Floian are described from the Nanba section in the Yiyang area,Hunan Province.Among them,Paradelograptus onubensis, Kiaerograptus bulmani,K.kutchini and Paratemnograptus isolatus of the Late Tremadoc are first found in China.Based on the current graptolite materials,the correspondingly complete graptolite zones of Upper Tremadocian in China are recognized as follows(in ascending order):the Adelograptus tenellus Zone,the Aorograptus victoriae Zone,the Araneograptus murrayi Zone and the Hunnegraptus copiosus Zone.In the Nanba section,the Hunnegraptus copiosus Zone is overlain directly by the Tetragraptus approximatus Zone,there is no hiatus below the base of Floian. 相似文献
13.
<正>A new family of so-called‘higher' planthoppers,Weiwoboidae fam.nov.,from the Lower Eocene of Yunnan is described.A new monotypic genus,Weiwoboa gen.nov.,with Weiwoboa meridiana sp.nov.is also described and illustrated.The characters of tegmen venation of the new family,its evolution,and supposed relationships are briefly discussed. 相似文献
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15.
LA-ICP-MS Zircon U-Pb Geochronology and Petrology of the Muchang Alkali Granite, Zhenkang County, Western Yunnan Province, China 总被引：4，自引：0，他引：4
<正>The Muchang composite intrusion is located about 14 km southeast of the Fengwei town and south of the Baoshan-Zhenkang block.The rift-related intrusion consists of the early-stage riebeckite nordmarkite in the east and west sides and the discontinuous marginal zone,the late-stage main body of dominant riebeckite granite,and minor aegirine granite.Studies on petrological geochemistry and LA-ICP-MS zircon U-Pb dating of the late-stage riebeckite granite,origin and evolution of the Muchang alkali granite and the relationship between the granite and the associated skarn-type Luziyuan Pb-Zn deposit are discussed in this paper.The results show that the Muchang alkali granites belong to A-type granites,which are characterized by enrichment in Al_2O_3,SiO_2,total alkali and Fe, depletion in MgO and CaO contents with high FeO_T/MgO ratios.The REE concentrations are relatively high,exhibiting highly fractionated LREE patterns with significantly Eu negative anomaly. The Muchang granites are obviously enriched in lithophile elements(e.g.,Rb,K,U and Th) and high field strength elements(e.g.,Zr,Hf,Nb,Y and Ga) with high 10000×Ga/Al ratios and depleted in Sr, Ba,Ti,Cr and Ni,which are similar to those of the A-type granites and quite different from those of S-type andⅠ-type granites.The LA-ICP-MS zircon dating results of the Muchang granite gave a weighted mean age of 266.2±5.4 Ma(2σ),suggesting that they were formed in the stage of extension at the end of post-collision at Middle Permian and the consumption of Paleo-Tethys ocean took place before 266 Ma. It is suggested that the unexposed intermediate-acid intrusive rocks in the Luziyuan ore district,which is the "sister" rocks material of the Muchang granites and related closely to Luziyuan Pb-Zn mineralization,were the product of Middle Permian. 相似文献
16.
Minfang Wang Youye Zheng Rongke Xu Yunguang Liu Fan Xiao Shanwen Cheng Xiangmin Sun 《中国地球化学学报》2014,33(1):65-76
The Shewushan gold deposit is located 16 km southwest of Jiayu County, Hubei Province, eastern China, which is the largest lateritic gold deposit in Asia, consisting of a series of mineralized faults containing gold grades of 1.0–19.5 g/t set within a larger, lower-grade(0.2–1.0 g/t) zone. According to the fluid inclusions study, the homogenization temperature ranges from 70–350℃, and concentrates between 140–220℃. The laser Rama results show that the CO2 and CH4 exist in mineralized fluid. In addition, the major and trace element and REE geochemical data show that the genesis of the siliceous rocks is hydrothermal genesis, formed by mineralized fluid bearing SiO2 transmitted along faults to the surface, and replace the carbonate rocks to begin deposition. Primary gold mineralization is attributed to hydrothermal activity that followed the main period of tectonic deformation of the Indosinian orogeny, which caused the regional detachment regime in southeast Hubei. The reversed fold and the fault system formed the fluid migration channel in the Shewushan area. EPMA results show that Au exists in arsenopyrite(850×10-6–1550×10-6 Au) and pyrite(470×10-6–1340×10-6 Au). Therefore, based on the above results and combined with the field observation, we suggest that the genesis of primary orebody in Shewushan deposit is carlin type, while not weathered residual type. 相似文献
17.
Huabin Hu Shuyin Niu Zhanyang Zhang Ye Tian Xiaoyu Liu Xicai Chen Haijiao Chen 《中国地球化学学报》2014,33(1):1-8
The Huangtuliang monzonitic granite outcrops on the northern side of the Huangtuliang gold mining district, Chicheng, North Hebei Province. Our predecessors only made isotopic age determination using the K-Ar method. Through LA-MC-ICP-MS zircon U-Pb dating and zircon Hf isotopic composition determination, this study acquired the age of 244.8±2.0 Ma(MSWD=0.57) on the basis of the weighed mean 206Pb/238U ratio, indicating that the Huangtuliang monzonitic granite was formed during the Middle Triassic period, which is the product of Early Indosinian magmatic activities in the region of North Hebei. εHf(t) values vary relatively evenly, within the range of-10.65--14.03, with an average of-12.14. The two-stage evolution model ages, tDM2, vary between 1943 and 2144 Ma, implying that the rock-forming materials of the Huangtiliang monzonitic granite mainly came from the Paleoproterozoic recirculated crustal materials, though a small quantity of enriched-mantle materials would have been involved. 相似文献
18.
<正>A new genus Microelectrona gen.nov.and species Microelectrona cladara sp.nov.of the extinct tribe Protodikraneurini of the leafhoppers(Cicadeilidae:Typhlocybinae) from the Eocene Baltic amber is described. The piece of amber containing leafhopper inclusion is broken,unveiling some of the morphological structures,and enabling their studies using scanning electron microscopy. 相似文献
19.
A naturally selenium-accumulating Cardamine sp. is growing in Yutangba Selenium Mining Field, Enshi area, Hubei Province, China, where the geochemical environment is selenium-enriched and endemic selenosis ever occurred in humans. The present study investigated the characteristics of accumulation, speciation and quantity of selenium in Cardamine sp. with HPLC-ICP-MS. Results show that Cardamine sp. can accumulate Se at most 1427 mg/kg in seedling leaves. Even after the biomass incensement of growing up, the plant still could accumulate Se up to several hundred of mg/kg in concentration. Moreover, the biomass enrichment coefficient （BEC） of Se is exceedingly high, in the seedling leaves mostly, higher than 50 mg/kg; in the range of 43.7-68 mg/kg; and the lowest value is higher than 3 mg/kg in mature fronds. Se is present in the plant predominantly in form of SeCys2 with the highest concentration in seeds; up to 1081 mg/kg as Se. In contrast, SeCysz levels are low during early growth period; they are 136.1 mg/kg as Se in seedling fronds and 39.4 mg/kg as Se in mature fronds, respectively. SeMet concentration is comparatively low; 10.6 mg/kg as Se in seedling frond and 5.3 mg/kg as Se in half mature fronds, respectively. This indicates that Cardamine sp. is extremely efficient in extracting Se from soil and translocating it into its above-ground biomass. Therefore, Cardamine sp., found in Yutangba Se Mining Field may be a new Se hyperaccumulator. It is still uncertain whether the Se-accumulation or detoxification of Cardamine sp. happens through the pathway of SeCys methylated to form Se-methylselenoCys or through the formation of Se-carboxymethyl- selenohomocysteine. Indeed, further study should be carried out on the determination of more Se species to explain the high Se hyperaccumulation in Cardamine sp. 相似文献
20.
The Tresca failure criterion is used regularly in geotechnical engineering to compute the failure loads of clay soils deforming under undrained conditions. When this criterion is used together with the finite element method a plastic flow rule must also be incorporated in the elasto-plastic soil model.
The effects of the flow rule on the performance of a non-linear analysis using an elastic perfectly plastic soil model obeying the Tresca failure criteria are discussed in this note. Application of this model in a three-dimensional analysis causes computational difficulties, due to the gradient discontinuities that exist at the corner of the Tresca yield surface. Such discontinuities can be removed from the yield (or failure) surface using different methods. Two of the most widely used methods in removing singularities from the yield surface and their overall performances in a three-dimensional finite element analysis are discussed.
The motivation for this study comes from a concern raised by Randolph and Puzrin [Randolph MF and Puzrin AM Upper bound limit analysis of circular foundations on clay under general loading. Geotechnique, (2003);53(9):785–796, [5]] about reported instances of under predictions of the collapse loads by finite element analysis [Taiebat HA and Carter JP Numerical studies of the bearing capacity of shallow foundations on cohesive soil subjected to combined loading. Geotechnique, (2000);50(4):409–418, [7]] and [Taiebat HA and Carter JP Bearing capacity of strip and circular foundations on undrained clay subjected to eccentric loads. Geotechnique, (2002);52(1):61–64, [8]], [Gourvenec S and Randolph M Effect of strength non-homogeneity on the shape of failure envelopes for combined loading of strip and circular foundations on clay, Geotechnique, (2003);53(6):575–586, [4]], when it is usually expected that finite element results should overestimate the true collapse loads. The intent of this study is to demonstrate and reiterate that although the finite element method is an extremely powerful analytical tool for solution of engineering problems, it is nevertheless subjected to approximation errors due to simplifications that are necessarily made to prevent other numerical difficulties. 相似文献